Poly(arylene ether) and an apparatus for producing the same

ABSTRACT

A poly(arylene ether) produced by combining a poly(arylene ether) solution with an antisolvent at a shear rate of greater than 50,000 sec −1 . The high shear mixing conditions produce a poly(arylene ether) dispersion in which the poly(arylene ether) solid contains reduced amounts of undesirably fine particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 10/769,043,filed on Jan. 30, 2004, now U.S. Pat. No. 7,151,158 which isincorporated herein by reference.

BACKGROUND

Poly(arylene ether) resins may be prepared by the oxidativepolymerization of a monohydric phenol in the presence of a solvent toform a solution in which the product poly(arylene ether) is soluble. Thepoly(arylene ether) may then be isolated by combining the solution withan antisolvent to precipitate the poly(arylene ether). In practice, itis very challenging to control these precipitations to provide a finalpoly(arylene ether) solid having consistent particle size. Inparticular, there is a need for a method of precipitating a poly(aryleneether) that reduces the amount of undesirably fine particles.

BRIEF SUMMARY

The above-described and other drawbacks and disadvantages are alleviatedby a method comprising: combining a poly(arylene ether) solution with anantisolvent to form a poly(arylene ether) dispersion comprising apoly(arylene ether) solid; wherein the poly(arylene ether) solutioncomprises a poly(arylene ether) and a solvent; and wherein saidcombining comprises mixing with a shear rate of greater than 20,000reciprocal seconds (sec⁻¹).

Other embodiments, including an apparatus for carrying out the method,are described in detail below.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a simplified diagrammatic view of a poly(arylene ether)isolation apparatus 10 including a high-shear mixing pump 50 forcombining a poly(arylene ether) solution and an antisolvent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Having extensively studied the precipitation of poly(arylene ether)resins under laboratory-scale, pilot plant, and manufacturingconditions, the present inventors have observed that it can be verydifficult to control the precipitation process in order to provide anisolated poly(arylene ether) resin having a low content of particlessmaller than 38 micrometers (“fines”). It is desirable to reduce finesbecause their presence may be associated with losses of the poly(aryleneether) during filtration and drying stages. Other methods may allow theisolation of powders having low content of fines, but they are notreadily and economically adaptable to a large-scale manufacturingfacility. There remains a need for an economical poly(arylene ether)preparation method that produces poly(arylene ether) powders having areduced content of fines.

The present inventors have surprisingly found that a poly(arylene ether)precipitate with reduced fines content may be obtained by combining apoly(arylene ether) solution and an antisolvent at a shear rate ofgreater than 20,000 sec⁻¹. This result is particularly surprisingbecause the high shear rate might have been expected to cause particleattribution and therefore undesirably small particle sizes. The shearrate is preferably greater than 50,000 sec⁻¹, more preferably at leastabout 60,000 sec⁻¹, still more preferably at least about 75,000 sec⁻¹,even more preferably at least about 100,000 sec⁻¹, yet more preferablyat least about 125,000 sec⁻¹. In one embodiment, the shear rate is lessthan about 500,000 sec⁻¹, preferably less than about 350,000 sec⁻¹, evenmore preferably less than about 250,000 sec⁻¹. The desired high shearmay be achieved using a pump comprising a stator and a rotor. The shearrate may then be defined by the equationshear rate=V×1000/Wwhere shear rate is expressed in units of sec⁻¹, V is thecircumferential linear velocity of the rotor, in meters per second, andW is the gap width defined by the stator and the rotor, in millimeters.In one embodiment, the stator and the rotor define a gap width of about0.01 to about 1 millimeter. Within this range, the gap width maypreferably be at least about 0.05 millimeter, more preferably at leastabout 0.10 millimeter. Also within this range, the gap width maypreferably be up to about 0.5 millimeter, more preferably up to about0.25 millimeter. In another embodiment, the rotor has a circumferentiallinear velocity of about 1 to about 100 meters per second. Within thisrange, the velocity may preferably be at least about 5 meters persecond, more preferably at least about 10 meters per second. Also withinthis range, the velocity may preferably be up to about 60 meters persecond, more preferably up to about 40 meters per second. Apparatussuitable for performing the high-shear combination of the poly(aryleneether) solution and the antisolvent is described, for example, inEuropean Patent No. 135,697 B1 to Schreiber. Suitable apparatus is alsocommercially available as, for example, the Siefer Trigonal SM 180centrifugal pump from Wilhelm Siefer GmbH & Co., Velbert, Germany.

There is no particular limit on the ratio in which the poly(aryleneether) solution and the antisolvent are combined. In one embodiment, thepoly(arylene ether) solution and the antisolvent are combined in aweight ratio of about 1:1 to about 1:10. Within this range, the ratiomay preferably be at least about 1:8, more preferably at least about1:6. Also within this range, the ratio may preferably be up to about1:2, more preferably up to about 1:3. In another embodiment, thepoly(arylene ether) solution and the antisolvent are combined in avolume ratio of about 1:1 to about 1:10. Within this range, the ratiomay preferably be at least about 1:8, more preferably at least about1:6. Also within this range, the ratio may preferably be up to about1:2, more preferably up to about 1:3.

The temperatures of the poly(arylene ether) solution and the antisolventimmediately before they are combined will vary according to manyfactors, including, for example, the poly(arylene ether) composition,the poly(arylene ether) intrinsic viscosity, the poly(arylene ether)concentration in the solution, the solvent type, the antisolvent type,and the weight ratio of poly(arylene ether) solution to antisolvent. Inone embodiment, the method comprises combining the poly(arylene ether)at a temperature of about 60 to about 100° C. with the antisolvent at atemperature of about 15 to about 60° C. Within these ranges, thepoly(arylene ether) solution temperature may be at least about 70° C.,or at least about 80° C.; and the poly(arylene ether) solutiontemperature may be up to about 95° C., or up to about 90° C. Also withinthese ranges, the antisolvent temperature may be at least about 20° C.,or at least about 25° C.; and the antisolvent temperature may be up toabout 55° C., or up to about 50° C. The temperature of the combinedpoly(arylene ether)-antisolvent mixture may preferably be about 30 toabout 55° C.

There is no particular limit on the type of poly(arylene ether) used inthe method. The term poly(arylene ether) includes polyphenylene ether(PPE) and poly(arylene ether) copolymers; graft copolymers; poly(aryleneether) ether ionomers; and block copolymers of alkenyl aromaticcompounds, vinyl aromatic compounds, and poly(arylene ether), and thelike; and combinations comprising at least one of the foregoing; and thelike. Poly(arylene ether)s per se, are known polymers comprising aplurality of structural units of the formula

wherein for each structural unit, each Q¹ is independently halogen,primary or secondary lower alkyl (e.g., alkyl containing up to 7 carbonatoms), phenyl, haloalkyl, aminoalkyl, hydrocarbonoxy,halohydrocarbonoxy wherein at least two carbon atoms separate thehalogen and oxygen atoms, or the like; and each Q² is independentlyhydrogen, halogen, primary or secondary lower alkyl, phenyl, haloalkyl,hydrocarbonoxy, halohydrocarbonoxy wherein at least two carbon atomsseparate the halogen and oxygen atoms, or the like. Preferably, each Q¹is alkyl or phenyl, especially C₁₋₄ alkyl, and each Q² is hydrogen. Inone embodiment, each Q¹ is methyl and each Q² is hydrogen or methyl. Inanother embodiment, each Q¹ is methyl and each Q² is hydrogen.

Both homopolymer and copolymer poly(arylene ether) are included. Thepreferred homopolymers are those containing 2,6-dimethylphenylene etherunits. Suitable copolymers include random copolymers containing, forexample, such units in combination with 2,3,6-trimethyl-1,4-phenyleneether units or copolymers derived from copolymerization of2,6-dimethylphenol with 2,3,6-trimethylphenol. Also included arepoly(arylene ether) containing moieties prepared by grafting vinylmonomers or polymers such as polystyrenes, as well as coupledpoly(arylene ether) in which coupling agents such as low molecularweight polycarbonates, quinones, heterocycles and formals undergoreaction in known manner with the hydroxy groups of two poly(aryleneether) chains to produce a higher molecular weight polymer. Poly(aryleneether)s of the present invention further include combinations comprisingat least one of the above.

In one embodiment, the poly(arylene ether) is the polymerization productof the at least one monohydric phenol and a dihydric phenol having thestructureHO—D—OHwherein D is a divalent aromatic radical. In one embodiment D has thestructure

wherein A¹ represents an aromatic group such as phenylene, biphenylene,naphthylene, etc. In some embodiments E may be an alkylene or alkylidenegroup including, for example, methylene, ethylene, ethylidene,propylene, propylidene, isopropylidene, butylene, butylidene,isobutylidene, amylene, amylidene, isoamylidene. When E is an alkyleneor alkylidene group, it may also consist of two or more alkylene oralkylidene groups connected by a moiety different from alkylene oralkylidene, such as an aromatic linkage; a tertiary amino linkage; anether linkage; a carbonyl linkage; a silicon-containing linkage; or asulfur-containing linkage including, but not limited to, sulfide,sulfoxide, sulfone; or a phosphorus-containing linkage including, butnot limited to, phosphinyl, phosphonyl. In other embodiments E may be acycloaliphatic group including, but not limited to, cyclopentylidene,cyclohexylidene, 3,3,5-trimethylcyclohexylidene, methylcyclohexylidene,2-[2.2.1]-bicycloheptylidene, neopentylidene, cyclopentadecylidene,cyclododecylidene, adamantylidene; a sulfur-containing linkage, such assulfide, sulfoxide or sulfone; a phosphorus-containing linkage, such asphosphinyl or phosphonyl; an ether linkage; a carbonyl group; a tertiarynitrogen group; or a silicon-containing linkage such as silane orsiloxy. R¹ represents hydrogen or a monovalent hydrocarbon group such asalkyl, aryl, aralkyl, alkaryl, or cycloalkyl. In various embodiments amonovalent hydrocarbon group of R¹ may be halogen-substituted,particularly fluoro- or chloro-substituted, for example as indichloroalkylidene. Each occurrence of Y¹ may be an inorganic atomincluding, but not limited to, halogen (fluorine, bromine, chlorine,iodine); an inorganic group including, but not limited to, nitro; anorganic group including, but not limited to, a monovalent hydrocarbongroup such as alkyl, aryl, aralkyl, alkaryl, or cycloalkyl, or an oxygroup such as OR², wherein R² is a monovalent hydrocarbon group such asalkyl, aryl, aralkyl, alkaryl, or cycloalkyl. In some particularembodiments Y¹ comprises a halo group or C₁-C₆ alkyl group. The letter“m” represents any integer from and including zero through the number ofpositions on A¹ available for substitution; “p” represents an integerfrom and including zero through the number of positions on E availablefor substitution; “t” represents an integer equal to at least one; “s”is either zero or one; and “u” represents any integer including zero.

When more than one Y¹ substituent is present, they may be the same ordifferent. When more than one R¹ substituent is present, they may be thesame or different. Where “s” is zero and “u” is not zero, the aromaticrings are directly joined by a covalent bond with no interveningalkylidene or other bridge. The positions of the hydroxyl groups and Y¹on the aromatic residues A¹ can be varied in the ortho, meta, or parapositions and the groupings can be in vicinal, asymmetrical orsymmetrical relationship, where two or more ring carbon atoms of thearomatic residue are substituted with Y¹ and hydroxyl groups.

Some illustrative, non-limiting examples of dihydric phenols include thedihydroxy-substituted aromatic hydrocarbons disclosed by name or formula(generic or specific) in U.S. Pat. No. 4,217,438 to Brunelle et al.Suitable dihydric phenols include, for example,6-hydroxy-1-(4′-hydroxyphenyl)-1,3,3-trimethylindane,4,4′-(3,3,5-trimethylcyclohexylidene)diphenol;1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane;2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol-A);4,4-bis(4-hydroxyphenyl)heptane;2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane;2,2-bis(4-hydroxy-3-methylphenyl)propane;2,2-bis(4-hydroxy-3-ethylphenyl)propane;2,2-bis(4-hydroxy-3-isopropylphenyl)propane;2,4′-dihydroxydiphenylmethane; bis(2-hydroxyphenyl)methane;bis(4-hydroxy-phenyl)methane; bis(4-hydroxy-5-nitrophenyl)methane;bis(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)methane;1,1-bis(4-hydroxyphenyl)ethane; 1,1-bis(4-hydroxy-2-chlorophenyl)ethane;2,2-bis(3-phenyl-4-hydroxyphenyl)-propane;bis(4-hydroxyphenyl)cyclohexylmethane;2,2-bis(4-hydroxyphenyl)-1-phenylpropane;3,5,3′,5′-tetrachloro-4,4′-dihydroxyphenyl)propane; 2,4′-dihydroxyphenylsulfone; 2,6-dihydroxy naphthalene; 6,6′-dihydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobiindane (sometimes know as “SBI”);hydroquinone; resorcinol; and C₁-C₃ alkyl-substituted resorcinols. In aparticular embodiment the dihydric phenol comprises bisphenol-A.Suitable dihydric phenols also include those containing indanestructural units such as, for example, is3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol, and1-(4-hydroxyphenyl)-1,3,3-trimethylindan-5-ol.

The poly(arylene ether) is typically prepared by the oxidative couplingof at least one monohydroxyaromatic compound such as 2,6-xylenol or2,3,6-trimethylphenol. Catalyst systems are generally employed for suchcoupling; they typically contain at least one heavy metal compound suchas a copper, manganese or cobalt compound, usually in combination withvarious other materials. The method may, optionally, further comprisepreparing the poly(arylene ether).

Particularly useful poly(arylene ether)s for many purposes are thosethat comprise molecules having at least one aminoalkyl-containing endgroup. The aminoalkyl radical is typically located in an ortho positionto the hydroxy group. Products containing such end groups may beobtained by incorporating an appropriate primary or secondary monoaminesuch as di-n-butylamine or dimethylamine as one of the constituents ofthe oxidative coupling reaction mixture. Also frequently present are4-hydroxybiphenyl end groups, typically obtained from reaction mixturesin which a by-product diphenoquinone is present, especially in acopper-halide-secondary or tertiary amine system. A substantialproportion of the polymer molecules, typically constituting as much asabout 90% by weight of the polymer, may contain at least one of theaminoalkyl-containing and 4-hydroxybiphenyl end groups.

There is no particular limit on the intrinsic viscosity of thepoly(arylene ether). For example, the poly(arylene ether) may have anintrinsic viscosity measured at 25° C. in chloroform of about 0.05 toabout 1.0 deciliters per gram (dL/g). Within the range, the intrinsicviscosity may be at least about 0.1, 0.2, 0.3, or 0.35 dL/g. Also withinthis range, the intrinsic viscosity may be up to about 0.8, 0.65, or 0.5dL/g. The method is particularly useful for controlling theprecipitation of low intrinsic viscosity poly(arylene ether) resins.Thus, in one embodiment, the poly(arylene ether) has an intrinsicviscosity of about 0.05 dL/g to about 0.3 dL/g. In another embodiment,the poly(arylene ether) comprises about 90 to about 99.9 weight percentof a first poly(arylene ether) having an intrinsic viscosity of about0.05 to 0.3 deciliters per gram and about 0.1 to about 10 weight percentof a second poly(arylene ether) having an intrinsic viscosity of greaterthan 0.3 to about 1.0 deciliters per gram.

The poly(arylene solution) may comprise any concentration ofpoly(arylene ether). For example, the poly(arylene ether) solution maycomprise about 10 to about 70 weight percent of the poly(arylene ether),based on the total weight of the poly(arylene ether) solution. Withinthis range, the poly(arylene ether) concentration may be at least about20 weight percent, or at least about 40 weight percent. Also within thisrange, the poly(arylene ether) concentration may be up to about 60weight percent, or up to about 50 weight percent. The optimumpoly(arylene ether) concentration will depend on variables including thepoly(arylene ether) composition, the poly(arylene ether) intrinsicviscosity, and the identity of the solvent.

There is no particular limit on the solvent employed in the method.Suitable organic solvents include aliphatic alcohols, ketones, aliphaticand aromatic hydrocarbons, chlorohydrocarbons, nitrohydrocarbons,ethers, esters, amides, mixed ether-esters, sulfoxides, and the like,and combinations thereof. In a preferred embodiment, the solventcomprises a C₆-C₁₈ aromatic hydrocarbon, including, for example,toluene, xylenes, and the like, and mixtures thereof. A highly preferredsolvent is toluene.

In one embodiment, the solvent comprises, based on the total weight ofthe solvent, about 70 to about 99.9 weight percent of a C₆-C₁₈ aromatichydrocarbon, and about 0.1 to about 30 weight percent of a poor solventsuch as, for example, a C₁-C₁₀ alkanol, a C₃-C₁₀ ketone, a C₅-C₁₀alkane, or the like, or a mixture thereof. In one embodiment, the poorsolvent comprises a C₃-C₈ aliphatic alcohol such as, for example,n-propanol, isopropanol, n-butanol, t-butanol, n-pentanol, or the like,or a combination thereof. A preferred C₃-C₈ aliphatic alcohol isn-butanol. In one embodiment, the solvent comprises a C₆-C₁₈ aromatichydrocarbon; a C₃-C₈ aliphatic alcohol; and methanol and/or ethanol,which acts as an antisolvent for the poly(arylene ether). The C₆-C₁₈aromatic hydrocarbon, the C₃-C₈ aliphatic alcohol, and the methanol orethanol may be combined in any proportion, but it may be preferred thatthe solvent comprise at least about 50 weight percent of the C₆-C₁₈aromatic hydrocarbon.

In another embodiment, the solvent is substantially free of any C₁-C₆alkanol. By substantially free, it is meant that the solvent comprisesless than about 0.1 weight percent of a C₁-C₆ alkanol. In thisembodiment, it is preferred that the solvent comprises no intentionallyadded C₁-C₆ alkanol.

The poly(arylene ether) solution is preferably a homogeneous solution.In other words, the poly(arylene ether) solution is preferably free ofundissolved solid particles, especially particles having any dimensiongreater than 1 micrometer. In one embodiment, the poly(arylene ether)solution does not exhibit a cloud point when cooled. For example, assolutions of poly(2,6-dimethyl-1,4-phenylene ether) in toluene areconcentrated, they may form a gelatinous phase without the discretesolid particles characteristic of a cloud point. A method of determiningthe cloud point of a poly(arylene ether) solution (and therefore ofdetermining whether a poly(arylene ether) exhibits such a cloud point)is described in U.S. Pat. No. 6,444,779 to Singh et al.

There is no particular limit on the antisolvent employed in the method.Suitable antisolvents include lower alkanols having one to about tencarbon atoms, such as methanol, and the like; ketones having three toabout ten carbon atoms, such as acetone, and the like; and alkaneshaving five to about ten carbon atoms, such as hexane; and the like; andcombinations thereof. A preferred antisolvent comprises methanol,ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, orthe like, or a mixture thereof. In one embodiment the antisolventcomprises methanol and at least one C₃-C₆ alkanol. Suitable C₃-C₆alkanols include, for example, n-propanol, isopropanol, n-butanol,isobutanol, t-butanol, n-pentanol, 2-methyl-1-butanol,2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol,2,2-dimethyl-1-propanol (neopentyl alcohol), cyclopentanol, 1-hexanol,2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol,2-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol,3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol,2-ethyl-1-butanol, 2,3-dimethyl-1-butanol, 2,3-dimethyl-2-butanol,2,2-dimethyl-1-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol,cyclopentylmethanol, 1-methylcyclopentanol, 2-methylcyclopentanol,3-methylcyclopentanol, cyclohexanol, and the like, and mixtures thereof.In another embodiment, the antisolvent comprises (a) methanol, and (b)isopropanol, n-butanol, or a mixture thereof. A highly preferredantisolvent comprises methanol.

In another embodiment, the antisolvent comprises about 60 to 99.8 weightpercent methanol, 0.1 to about 30 weight percent toluene, and 0.1 toabout 10 weight percent water. Preferably, the antisolvent comprisesabout 70 to about 90 weight methanol, about 5 to about 30 weight percenttoluene, and about 1 to about 6 weight percent water. More preferably,the antisolvent comprises about 75 to about 85 weight percent methanol,about 15 to about 25 weight percent toluene, and about 1.5 to about 5weight percent water.

The temperatures of the poly(arylene ether) solution and the antisolventimmediately before they are combined will vary according to manyfactors, including, for example, the poly(arylene ether) composition,the poly(arylene ether) intrinsic viscosity, the poly(arylene ether)concentration in the solution, the solvent type, the antisolvent type,and the weight ratio of poly(arylene ether) solution to antisolvent. Inone embodiment, the method comprises combining the poly(arylene ether)at a temperature of about 60 to about 100° C. with the antisolvent at atemperature of about 15 to about 60° C. Within these ranges, thepoly(arylene ether) solution temperature may be at least about 70° C.,or at least about 80° C.; and the poly(arylene ether) solutiontemperature may be up to about 95° C., or up to about 90° C. Also withinthese ranges, the antisolvent temperature may be at least about 20° C.,or at least about 25° C.; and the antisolvent temperature may be up toabout 55° C., or up to about 50° C. The temperature of the combinedpoly(arylene ether)-antisolvent mixture may preferably be about 30 toabout 55° C.

In another embodiment, the method may, optionally, further compriseconcentrating the poly(arylene ether) solution prior to the combiningthe poly(arylene ether) solution with the antisolvent. In oneembodiment, concentrating the poly(arylene ether) solution is conductedin a continuous process section comprising a heat exchanger, a flashunit, and a circulation pump. Optionally, part of the concentratedsolution product discharged from the flash unit may be recycled to theinlet of the heat exchanger. In one embodiment, the flash unit isoperated at a pressure less than one atmosphere, and the temperature ofthe poly(arylene solution) in the heat exchanger is greater than theboiling point of the solvent at the actual pressure in the flash unit.In this embodiment, the lower pressure in the flash unit results inadiabatic flashing of part of the solvent. Preconcentrating thepoly(arylene ether) solution may comprise maintaining a flash vessel ata pressure, P, heating the poly(arylene ether) solution to atemperature, T, above the boiling point of the solvent at pressure P,introducing the heated poly(arylene ether) solution to the flash vesselto evaporate a portion of the solvent and form a concentratedpoly(arylene ether) solution, and recirculating a portion of theconcentrated poly(arylene ether) solution to a point upstream of theflash vessel.

Combining the poly(arylene ether) solution with the antisolvent forms apoly(arylene ether) dispersion. The method may, optionally, furthercomprise separating the poly(arylene ether) solid from the poly(aryleneether) dispersion. In one embodiment, separating the poly(arylene ether)solid from the poly(arylene ether) dispersion comprises filtration. Inanother embodiment, separating the poly(arylene ether) solid from thepoly(arylene ether) dispersion comprises centrifugation. Suitablefiltration apparatuses include rotating filters, continuous rotaryvacuum filters, continuous moving bed filters, batch filters, and thelike. Suitable solid/liquid separation apparatuses include continuoussolid/liquid centrifuges.

The method allows control of the particle size distribution of theisolated poly(arylene ether) solid. The desired particle sizedistribution may vary as a function of, for example, the poly(aryleneether) composition and intrinsic viscosity. In one embodiment, theisolated poly(arylene ether) solid has a number-average mean particlesize of about 200 micrometers to about 1,000 micrometers. Within thisrange, the mean particle size may be at least about 300 micrometers.Also within this range, the mean particle size may be up to about 900micrometers, or up to about 800 micrometers, or up to about 700micrometers.

The method may, optionally, further comprise treating the poly(aryleneether) with a functionalizing agent comprising (a) at least onecarbon-carbon double bond or carbon-carbon triple bond and (b) at leastone functional group selected from carboxylic acid, acid anhydride, acidamide, imide, ester, amino, hydroxy, and the like. Suitablefunctionalizing agents include, for example, maleic acid, fumaric acid,maleic anhydride, maleimides such as N-phenylmaleimide and1,4-phenylene-bis-methylene-α,α′-bismaleimide, maleic hydrazide,methylnadic anhydride, fatty oils (e.g., soybean oil, tung oil, linseedoil, sesame oil), unsaturated carboxylic acids such as acrylic acid,crotonic acid, methacrylic acid and oleic acid, unsaturated alcoholssuch as allyl alcohol and crotyl alcohol, and unsaturated amines such asallylamine. A preferred functionalizing agent comprises maleicanhydride. In one embodiment, the poly(arylene ether) is treated withthe functionalizing agent in solution or slurry prior to precipitation.In another embodiment, an isolated poly(arylene ether) may be treatedwith a gaseous functionalizing agent. Other functionalizing agents, aswell as functionalizing methods, are described, for example, in U.S.Pat. No. 4,888,397 to van der Meer et al., and Japanese PatentPublication No. 2003-183385 to Tokiwa et al.

One embodiment is a method of precipitating a poly(arylene ether),comprising: combining a poly(arylene ether) solution with an antisolventto form a poly(arylene ether) dispersion comprising a poly(aryleneether) solid; wherein the antisolvent comprises an alkanol having one toabout ten carbon atoms; wherein the poly(arylene ether) solutioncomprises a poly(arylene ether) and a solvent; wherein the poly(aryleneether) comprises a poly(2,6-dimethyl-1,4-phenylene ether), apoly(2,6-dimethyl-1,4-phenylene ether-co-2,3,6-trimethyl-1,4-phenyleneether), or a mixture thereof; wherein the solvent comprises a C₆-C₁₈aromatic hydrocarbon; and wherein said combining comprises mixing with ashear rate of greater than 60,000 sec⁻¹.

Another embodiment is a method of precipitating a poly(arylene ether),comprising: combining a poly(arylene ether) solution with an antisolventto form a poly(arylene ether) dispersion comprising a poly(aryleneether) solid; wherein the antisolvent comprises methanol; wherein thepoly(arylene ether) solution comprises a poly(arylene ether) and asolvent; wherein the poly(arylene ether) comprises apoly(2,6-dimethyl-1,4-phenylene ether) having an intrinsic viscosity ofabout 0.05 to about 0.3 deciliters/gram at 25° C. in chloroform; whereinthe solvent comprises toluene; and wherein said combining comprisesmixing with a shear rate of greater than 75,000 sec⁻¹.

Another embodiment is a poly(arylene ether) prepared by any of the abovemethods. In one embodiment, the isolated poly(arylene ether) comprisesless that 10 weight percent, preferably less than 5 weight percent, morepreferably less than 2 weight percent, of particles smaller than 38micrometers. It will be understood that “smaller than 38 micrometers”refers to an equivalent spherical diameter less than 38 micrometers. Oneadvantage of the invention is that poly(arylene ether) solids preparedby the method exhibit improved flow properties. For example, thepoly(arylene ether) may exhibit a flowability value of about 70 to 100.Within the range of about 70 to 100, the flowability value maypreferably be at least about 75, more preferably at least about 82.Flowability may be determined by measuring percent compressibility.Percent compressibility, % C, is determined according to the equation

${\%\mspace{14mu} C} = {\frac{{PBD} - {ABD}}{PBD} \times 100}$where PBD is the packed bulk density and ABD is the aerated bulkdensity. Compressibility may be measured with commercially availableinstrumentation, such as, for example, a Hosakawa powder testing deviceavailable from Hosokawa Micron Powder Systems, 10 Chatham Road Summit,N.J. 07901, USA. There is an inverse correlation between percentcompressibility values and flowability values, as shown in Table 1,below. In Table 1, percent compressibility is abbreviated “Comp”, andflowability is abbreviated “Flow”. Thus, preferred percentcompressibility values are 0 to about 20, preferably 0 to about 17.5,more preferably 0 to about 14.

TABLE 1 Comp Flow 0.0 100 1.0 100 2.0 100 3.0 100 4.0 100 5.0 100 6.0 986.5 97 7.0 96 7.5 95 8.0 94 8.5 93 9.0 92 9.5 91 10.0 90 10.5 89 11.0 8811.5 87 12.0 86 12.5 85 13.0 84 13.5 83 14.0 82 14.5 81 15.0 80 15.5 7916.0 78 16.5 77 17.0 76 17.5 75 18.0 74 18.5 73 19.0 72 19.5 71 20.0 7020.5 69 21.0 68 21.5 67 22.0 66 22.5 65 23.0 64 23.5 63 24.0 62 24.5 6125.0 60 25.5 59 26.0 58 26.4 57 26.7 56 27.0 55 27.2 54 27.5 53 28.0 5228.2 51 28.5 50 28.8 49 29.0 48 29.4 47 29.7 46 30.0 45 30.2 44 30.5 4330.8 42 31.0 41 31.4 40 31.7 39 32.0 38 32.2 37 32.5 36 32.8 35 33.0 3433.4 33 33.7 32 34.0 31 34.2 30 34.5 29 34.8 28 35.0 27 35.4 26 35.7 2536.0 24 36.2 23 36.5 22 36.8 21 37.0 20 37.5 19 38.0 18 38.5 17 39.0 1639.5 15 40.0 14 40.5 13 41.0 12 41.5 11 42.0 10 42.5 9 43.0 8 43.5 744.0 6 45.0 5 46.0 <5

One embodiment is an apparatus for preparing a poly(arylene ether),comprising: means for preparing a poly(arylene ether) solutioncomprising a poly(arylene ether) and a solvent; means for combining thepoly(arylene ether) solution and an antisolvent at a shear rate ofgreater than 50,000 sec⁻¹ to form a poly(arylene ether) dispersioncomprising a poly(arylene ether) solid; and means for separating thepoly(arylene ether) solid from the poly(arylene ether) dispersion toform an isolated poly(arylene ether) solid. The poly(arylene ether)solution may be prepared by polymerizing a monohydric phenol in asolvent. Alternatively, the poly(arylene ether) solution may be preparedby dissolving a previously isolated poly(arylene ether) in a solvent.FIG. 1 illustrates one embodiment of a poly(arylene ether) isolationapparatus 10. Optional reactor 20 is used to polymerize a monohydricphenol in solvent to form a poly(arylene ether) solution 510. Thepoly(arylene ether) solution 510 is then concentrated by solvent removalin optional preconcentration unit 30 to form a concentrated poly(aryleneether) solution 520. The preconcentration unit 30 may comprise a heatexchanger 32, a flash evaporation unit 34, and a recirculation pump 36.Antisolvent 530, from antisolvent reservoir 40, is combined with theconcentrated poly(arylene ether) solution 520 in high-shear mixing pump50 to form poly(arylene ether) dispersion 540. The poly(arylene ether)dispersion 540 is pumped to an optional precipitation tank 60 where itis stirred and released as aged poly(arylene ether) dispersion 550. Theaged poly(arylene ether) dispersion 550 is separated by optionalcentrifuge 70 into combined solvent and antisolvent 560 and poly(aryleneether) solid 570. The poly(arylene ether) solid 570 conveyed to optionaldrier 80, which produces dried poly(arylene ether) solid 580.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLE 1 COMPARATIVE EXAMPLE 1

A solution of 38 weight percent poly(2,6-dimethyl-1,4-phenylene ether)in toluene was prepared. The poly(2,6-dimethyl-1,4-phenylene ether) hadan intrinsic viscosity of 0.46 deciliters/gram in toluene at 25° C. Thesolution, at a temperature of 82° C., was combined with antisolventconsisting of 78% methanol, 19% toluene and 3% water at a temperature of30° C., in a volume ratio of 1:5, respectively. For Example 1, thesolution and the antisolvent were combined using a high shear pumpcharacterized by a shear rate of 180,000 sec⁻¹, a stator-rotor gap widthof 0.15 millimeters, and a circumferential linear velocity of 27meter/second. For Comparative Example 2, the solution and antisolventwere combined in a stirred tank with an agitator having a rotation rateof 130 rpm and an energy input about forty times less than that of thehigh shear pump of 130. The precipitates thus obtained were filtered,dried, and characterized by particle size analysis using a Malvern PSD(particle size distribution) analyzer, which uses a laser lightdispersion technique to determine the weight percent of particlessmaller than 38 micrometers. The results, presented in Table 2, showthat the Example 1 precipitate had a substantially lower content of“fines” than did the Comparative Example.

TABLE 2 Ex. 1 C. Ex. 1 weight percent of particles <38 micrometers 4.112.1

EXAMPLE 2, COMPARATIVE EXAMPLE 2

The procedure of Example 1 and Comparative Example 1 was repeated,except that the intrinsic viscosity of thepoly(2,6-dimethyl-1,4-phenylene ether) was 0.40 deciliters/gram, and thepoly(arylene ether) solution contained 42% ofpoly(2,6-dimethyl-1,4-phenylene ether). The results, presented in Table3, again show that high shear mixing produces an isolated poly(aryleneether) having a reduced content of undesirably small particles.

TABLE 3 Ex. 1 C. Ex. 2 weight percent of particles <38 micrometers 2.610.7

While the invention has been described with reference to a preferredembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing fromessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety.

1. A poly(arylene ether) prepared by a method comprising: combining apoly(arylene ether) solution with an antisolvent to form a poly(aryleneether) dispersion comprising a poly(arylene ether) solid; wherein thepoly(arylene ether) solution comprises a poly(arylene ether) and asolvent; and wherein said combining comprises mixing with a shear rateof greater than 50,000 sec⁻¹ to about 500,000 sec⁻¹.
 2. The poly(aryleneether) of claim 1, comprising less that 10 weight percent of particlessmaller than 38 micrometers.
 3. The poly(arylene ether) of claim 1,having a percent compressibility of 0 to about 20 percent.
 4. Thepoly(arylene ether) of claim 1, wherein the poly(arylene ether)comprises a plurality of structural units of the formula

wherein for each structural unit, each Q¹ is independently selected fromhalogen, C₁-C₇ primary or secondary alkyl, phenyl, C₁-C₇ haloalkyl,C₁-C₇ aminoalkyl, C₁-C₇ hydrocarbonoxy, and C₂-C₇ halohydrocarbonoxywherein at least two carbon atoms separate the halogen and oxygen atoms;and each Q² is independently selected from hydrogen, halogen, C₁-C₇primary or secondary alkyl, phenyl, C₁-C₇ haloalkyl, C₁-C₇hydrocarbonoxy, and C₂-C₇ halohydrocarbonoxy wherein at least two carbonatoms separate the halogen and oxygen atoms.
 5. The poly(arylene ether)of claim 4, wherein each Q¹ is methyl and each Q² is hydrogen or methyl.6. The poly(arylene ether) of claim 4, wherein each Q¹ is methyl andeach Q² is hydrogen.
 7. The poly(arylene ether) of claim 4, wherein thepoly(arylene ether) is the polymerization product of the at least onemonohydric phenol and a dihydric phenol having the structureHO-D-OH wherein D is a divalent aromatic radical.
 8. The poly(aryleneether) of claim 1, wherein the poly(arylene ether) comprises afunctional group derived from a functionalizing agent comprising (a) atleast one carbon-carbon double bond or carbon-carbon triple bond and (b)at least one functional group selected from carboxylic acid, acidanhydride, acid amide, imide, ester, amino, hydroxy, and the like.
 9. Anapparatus for preparing a poly(arylene ether), comprising: means forpreparing a poly(arylene ether) solution comprising a poly(aryleneether) and a solvent; means for combining the poly(arylene ether)solution and an antisolvent at a shear rate of greater than 50,000 sec⁻¹to form a poly(arylene ether) dispersion comprising a poly(aryleneether) solid; and means for separating the poly(arylene ether) solidfrom the poly(arylene ether) dispersion to form an isolated poly(aryleneether) solid.
 10. The apparatus of claim 9, further comprising means forconcentrating the poly(arylene ether) solution prior to said combiningthe poly(arylene ether) solution and an antisolvent.
 11. The apparatusof claim 10, wherein the means for concentrating the poly(arylene ether)solution comprises a heat exchanger, a flash vessel, and recirculationloop.